sectionone Posted January 15, 2014 Report Share Posted January 15, 2014 The gearbox breather tube on my 07 pro goes to the atmosphere. I don't see a reason why it would go to the carb. If I was the buyer I would want a refund because even a 10 year old bike in good running order shouldn't seize unless you are going full throttle up a mountain for miles. Trials bikes can race 20 minute endurocross races with no problem. Quote Link to comment Share on other sites More sharing options...
ourian Posted January 15, 2014 Report Share Posted January 15, 2014 I'd go for 1. waterpump seal failure 2. coolant drains into gearbox 3. engine boils dry and overheats 4. impellor threads melt and hot spot develops 5. cylinderhead o ring cracks allowing exhaust into cylinder head jacket 6. cylinder head cracks and shrapnel enters cylinder 7. piston hits piece of shrapnel and slams into cylinder head (mark on cylinder head opposite hole) 8. cylinder wall scored due to overheating. The initial failure could also have been caused by fan not kicking in, radiator cap not on properly or leaking or loss of coolant from another orifice/leak. Without a detailed analysis of all the components involved diagnosis of the original cause of failure can only be guesstimated. Quote Link to comment Share on other sites More sharing options...
ourian Posted January 15, 2014 Report Share Posted January 15, 2014 PPS. the bits of metal in the pump photo were found in the water pump but the "mechanic"!!!!! says that the pump was the cause as the threads in the plastic impeller were stripped !!!!!!!!!!!! HELL If this was true why are they not covered in pink stuff? If the pipe from the gearbox breather was disconnected from the carb and both the carb and the gearbox breather were vented to atmosphere, then the mixture would become weak as the carb would be now drawing air in via the vent. Weak mixture = hotspots If you have photos of the changes, then I would tell him to take it up with the mechanic who cut and spliced the pipes. Quote Link to comment Share on other sites More sharing options...
jse Posted January 15, 2014 Report Share Posted January 15, 2014 Hi All, Again... What a story. For me this is turning bizarre! Went to the garage where the bike is and back today total time 6 hours.... Wanted to know if the carb had some pink (oil and water mix) in it and take some more detailed photos......Because the last time that the pump seal went the engine stopped because of the “pink stuff” in the carb ( for sure it wouldn’t burn) ummmmm! it get’s there I guess by way of the gearbox breather, that goes from the gearbox cover to the carb. Guess its a combination of the added liquid level (coolant with the oil) and the heat pressure in the box with the hot coolant, plus the carb suck? In the clear tube you could see the pink. I wanted to do this as “IF” the pump was the original cause of the problem like last time, then the pink in the carb would have cut the engine in a short time and the head and probably other parts would not have been damaged so drastically if at all, like last time! Arrive..... the pipe is cut and another pipe is fitted that goes to atmosphere along with the one that’s been cut! So I ask who had changed the pipes? The “!!!!!! MECHANIC!!!!” says it wasn’t connected and that it’s not important and points to a Honda that has a gearbox pipe that goes to atmosphere (......He insisted that it would never of been connected! P.S this guy is NOT a GG service bloke. I arrive home look at the sales photos taken a couple of weeks ago to advertise the machine and it’s clear that its connected before the bike was taken away.... also in the same photo it seems that the mixture screw is in a different place..........ummm! I looked at some 07 pro photos and it doesn’t seem connected but on mine (250 TXTI pro 03) (yes TXTI?)it was always connected HELP! When was this changed and does the pipe make a difference to the carburetion mix? ..... guess you know where I’m going! (out of me head) J) Think there’s a call to the nice guys at Gas Gas UK tomorrow. PPS. the bits of metal in the pump photo were found in the water pump but the "mechanic"!!!!! says that the pump was the cause as the threads in the plastic impeller were stripped !!!!!!!!!!!! HELL The trans breather hose is NEVER connected to the carb. Jon. ps. I'm not aware of a "TXTI" model. The 02' Pro was a "TXXI" model but known as the TXT Pro 03' forward. Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted January 16, 2014 Report Share Posted January 16, 2014 Phil 0925, Did you think to get a sample of the fuel from the tank? Would be a good way to check if the new owner had put in straight gas with no oil. No oil can also lead to severe overheating with essentially the same result. Quote Link to comment Share on other sites More sharing options...
phil0925 Posted January 16, 2014 Author Report Share Posted January 16, 2014 Hi Jon and All, My fault sorry. On the tank is TXT PRO 03 on the Radiator grill plastic cover is TXXI. (NOT TXTI as I typed). oppps. Had an email late last night from the mechanic saying that the guy (the buyer) admitted he'd changed it! ??? I've no idea why! I tend to think that ourian is correct but I will try and get some info from GG UK today and keep you posted especially about the pipe originally being connected. I do see that on a 07 photo its to atmosphere so I guess either someone befor I bought it changed it or its correct for this particular bike? The bits found in the pump and the pump parts were all cleaned a bit. The impeller has a white stress line in one of the vains so for me I conclude that the pump was running in that the parts got to the pump and if the pump impeller had not been turning because of the threads being stipped then the impeller vain would not have a white stress line mark. The pump seal two lips looked good apart from where the mechanic used a screw driver to remove it. The shaft has two nice clean polished marks where the seal lips run.....Therefore for me the pump was not the cause but probably a symptom. Not sure how I could get the fuel and oil mix tested so I didn't get a sample. Thanks again to all P Quote Link to comment Share on other sites More sharing options...
ourian Posted January 16, 2014 Report Share Posted January 16, 2014 I can understand a sump breather venting to a carb on a four stroke, but gearboxes are usually vented to atmosphere. Although Gas Gas may have tried something different on this model. I would have thought that the pipe from the carb is probably an overflow from the float bowl and at some point on this bike prior to you owning it, has been connected to the gearbox vent (for what ever reason) If the buyer had weakened the mixture and a hot spot occurred and then the cylinder head cracked producing a hole and shrapnel, wouldn't the bike have immediately stopped before dumping coolant into the gearbox? As the only place the coolant can enter the gearbox is via the water pump seal. Or is it that he weakened the mixture causing the engine to run hot, which in turn caused the water pump seal to fail? As for testing the fuel, a simple way is dip a piece of paper in the fuel, allow the petrol to evaporate and if there is oil present, it will leave a film of oil on the paper and as most two stoke oil is coloured either red or blue will stain the paper. Quote Link to comment Share on other sites More sharing options...
big_red_bike Posted January 16, 2014 Report Share Posted January 16, 2014 Hi again i think you are looking at the wrong thing with the carb and vents.I still think it was the head leaking which would increase pressure in the cooling system forcing coolant past the pump seal into the gearbox.The broken pump most likely happened after ,as when the engine was running coolant would have been flowing from the pump up to the cylinder,the engine would have stopped before the metal fragments reached the pump.after the engine stopped the fragments could have dropped down to the pump and when he tried to restart the engine it would have stripped the impellor threads. Quote Link to comment Share on other sites More sharing options...
totalshell Posted January 16, 2014 Report Share Posted January 16, 2014 all very interesting but missing the point by a mile.. you sold the bike it appears that the buyer has made several modifications/ adjustments since then and before the damamge. all seem to agree that this didnt happen in the blink of an eye and that is use beyond the first noticable symtoms has led to considerablly more damage what does french law say.. expect.. Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted January 16, 2014 Report Share Posted January 16, 2014 .... If the buyer had weakened the mixture and a hot spot occurred and then the cylinder head cracked producing a hole and shrapnel, wouldn't the bike have immediately stopped before dumping coolant into the gearbox? As the only place the coolant can enter the gearbox is via the water pump seal. Or is it that he weakened the mixture causing the engine to run hot, which in turn caused the water pump seal to fail? As for testing the fuel, a simple way is dip a piece of paper in the fuel, allow the petrol to evaporate and if there is oil present, it will leave a film of oil on the paper and as most two stoke oil is coloured either red or blue will stain the paper. Clearly, the engine got way to hot. With the cooked O-rings in the head, I think it was hot for a long time. The real question in my opinion is: "what caused the overheating?" Ourian provided a theory that is certainly plausible. I will provide a slightly different one. My theory is the use of straight fuel (no pre-mix). Engine gradually got hotter and hotter from lack of oil. O-ring cooked and stopped sealing and head possibly distorted. Pressure from combustion entered water jacket forcing coolant past the water pump seal into the gearbox. Head go so hot that material failure occurred. Some shrapnel went into water jacket and fell down into pump. Some shrapnel fell into cylinder and attached to piston. Piston shrapnel scratched cylinder wall. Engine stopped turning. In either case, the engine would have continued to run for some time after the initial fault and there probably would have been a loss of performance before the final engine failure. *** I like the idea of using paper to check for oil in the gas. I had some 2 stroke oil a while ago that did not have any color ( bad design - it should have color) but you can actually feel the difference by dipping your fingers in the fuel and rubbing them together - but it is not a perfect science. *** BTW Phil, I feel your pain on seeing a piece of equipment that you have enjoyed and taken care of for years, to be damaged so severely right after you sell it. I do not think you did anything wrong here. Don't let your emotional attachment to the bike cloud your thinking on the facts. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted January 17, 2014 Report Share Posted January 17, 2014 I would be inclined to agree with # 32 diagnosis - initiated by gradual coolant loss. Having said the above I also wondered is the combustion chamber is the right shape or has it been machined out (excessively) at some time to reduce compression. Need to compare it to a known standard head. The cylinder head metal looks very thin - manufacturing fault? I have never seen cylinder head metal this thin although I have not seen a broken pro head before. The only time I have seen heads break is by hydraulic pressure when the bike has been dropped in a river or when bits of piston, ring, big end or main bearings have been punched thought it. Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted January 17, 2014 Report Share Posted January 17, 2014 ... The cylinder head metal looks very thin - manufacturing fault? I have never seen cylinder head metal this thin although I have not seen a broken pro head before... I think it just looks very thin by the lighting and photograph angle. Look at the thickness of the bits that were removed from the water pump. They are an indication of the material thickness of the head. Quote Link to comment Share on other sites More sharing options...
lineaway Posted January 18, 2014 Report Share Posted January 18, 2014 I`d flat out ask him what oil and mix he used. I`ve got two nephews that can break any motorcycle in just a matter of days. That seems to be the case of just abuse, deliberate or not. I`ve never seen a head like that. Was the rod locked up? Quote Link to comment Share on other sites More sharing options...
axulsuv Posted January 18, 2014 Report Share Posted January 18, 2014 I`d flat out ask him what oil and mix he used. I`ve got two nephews that can break any motorcycle in just a matter of days. That seems to be the case of just abuse, deliberate or not. I`ve never seen a head like that. Was the rod locked up? My son's resemble that remark ... (don't worry dad can fix it ...) 1 Quote Link to comment Share on other sites More sharing options...
wayne509 Posted January 18, 2014 Report Share Posted January 18, 2014 At our trial yesterday an older chap managed two sections before his bike broke, something to do with the cylinder head. He only just bought the bike that week from someone local or relatively local. Now I don't know if the old fella has been back to the seller, but I personally think it's pretty bad form that a new owners bike "blows" up first time out and the previous owner just shruggs his shoulders and say tough titties, which is pretty much what most in this topic are suggesting. Just for your information on that matter ..... It was myself, well my eldest lad that sold the gentleman that bike. The only reason he sold it was as he was moving to a bigger CC bike. As soon as we heard what had happened ( suspected head gasket) I sent him a message on the local forum offering to pay for any parts needed and also to carry out the work needed. We feel terrible about what happened and want to help in anyway we can. 3 Quote Link to comment Share on other sites More sharing options...
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